The present invention relates generally to the field of video capture; more particularly, to video camera systems having information processing capabilities for uploading pictures to a web server.
A web camera (i.e., xe2x80x9cwebcamxe2x80x9d) system consists of a video camera plus software that runs on a personal computer to periodically upload an image from the camera to a web page. The basic purpose of a web camera system is to post a reasonably live picture on a user-specified web page. Many webcam systems upload images on a periodic basis; for example, uploading an image once per hour.
FIG. 1 illustrates a web camera system 10, which is typical of the prior art. System 10 includes a video camera 11 that outputs a captured video image to a personal computer (PC) 12. Software running on PC 12 functions to periodically upload the captured video image to an Internet web page (i.e., a web server) shown in FIG. 1 by block 13. Internet service providers (ISPs) commonly provide their patrons with a certain allocation of web page space for personal use. This allows the user to upload images onto their web page periodically; with the frequency of uploading being dependent on the particular type of connection offered by the ISP.
Presently, there are two shareware products in existence that relate to web cameras: Ispy(trademark) and Webcam32(trademark). The Ispy webcam software functions to grab video images, save them as JPEG files, and then send the saved images automatically to a user-specified home page via the connection provided by the users""ISP. Ispy runs under Windows(trademark) 95, Windows 98 and Windows NT 4.0; it also works with any video for Windows-compatible cameras and frame grabbers. Webcam32 is a Windows 95, Windows 98 and Windows NT application that allows video camera images to be displayed within a web page. Like Ispy, Webcam32 software is able to upload images to a web server to allow images to be obtained directly from the page. Both of these products include various simple image-processing features such as captioning of photos, day/time stamping, and text additions.
Webcam32(trademark) software also offers rudimentary motion detection, which is of primary use in security surveillance applications. For example, the Webcam32(trademark) software allows images to be uploaded when, say, 25% of the pixels in the image frame change from one image frame to the next. Although this motion-detecting feature of the software product is useful in limited types of motion detection applications (e.g., security surveillance), it is not useful for different applications. For example, if the web camera system is intended for use in observing and recording wildlife activity, then this type of rudimentary motion detection does not work well.
Another problem with today""s webcam systems is the conflict between the desire to minimize the number of times the web camera contacts the ISP and the to capture xe2x80x9cinterestingxe2x80x9d pictures (i.e., those containing certain kinds of motion). Most security surveillance type of web camera systems have a low threshold that results in the taking of many pictures whenever activity is detected. Uploading many pictures onto a web page presents a serious bandwidth problem.
Furthermore, existing products such as Ispy and Webcam32 only provide the ability to capture images on a given schedule, e.g., once per hour, or whenever motion occurs, regardless of how often. If set to capture on a predetermined schedule, images that may be of interest to the user may end up being ignored. On the other hand, if the software is set to upload a video image whenever motion is detected, scenes containing frequent motion can tie up the user""s phone lines.
Thus, there is a need for a web camera system that overcomes the problems inherent in the prior art.
The present invention is a camera system for connection to a web server. The system comprises a video camera and a processor that periodically uploads images captured by the video camera in accordance with one of a plurality of motion detection algorithms. A first motion detection algorithm captures a current image frame when a pixel comparison between successive image frames exceeds a predetermined threshold.